T. 0. Bosworfh — Origin of Upper Keuper, Leicestershire. 355 



the case. Except at a distance from the older rocks, any traces of 

 fractures in the Keuper are extremely rare, and there has apparently 

 been little or no post-Triassic faulting in Charnwood. So that it seems 

 probable that the beds were deposited with their present inclinations, 

 somewhat in the manner of the loess. 



JS'ear the rocks the marl contains grit and stones, and there is 

 generally a breccia at the base. The stones are of varied sizes ; 

 in some cases worn and in some cases very angular, but never 

 smooth like ordinarj- pebbles. They are in a remarkably fresh 

 condition, and often occur in bands in the marl, recalling the 

 stone beds in the Persian deserts described by Blanford. In South 

 Leicestershire they are much worn and fretted, and of very 

 irregular shapes. They are generally pitted and sometimes polished, 

 A j-ear ago the section along the south end of Croft Quarry showed 

 a 10 foot layer of these stones lying in a matrix of gritty marl. 

 Similar stones occur throughout the 30 feet of marl above, and 

 they are often situated with their grooves and ridges parallel with the 

 bedding, as though they had been carved in situ. Each stone is 

 surrounded by a thin red skin consisting largely of sulphates and 

 carbonates of calcium and magnesium. This skin may be due to 

 mineral matter filling up small spaces between the stone and the 

 marl. Such spaces might well be caused by alternate expansion, and 

 contraction of volume, under the influence of temperature changes so 

 marked in desert regions. 



The grit particles at Croft are subangular, and some of the green 

 bands are almost entirely composed of them. At Mountsorrel 

 and at Groby there are both worn and angular stones in the 

 Keuper, and some of them are very large. In Cocklow Wood 

 very rounded examples are seen in the bed of a pre-Triassic gully. 

 Considering that the summit of the hill on whose side they occur 

 must have been within 200 yards, their shape is somewhat remarkable. 

 The position of this gullj^ has evidently been determined by a belt of 

 shattered rock beneath. A similar example occurs at Groby, but in 

 this case the stones are angular. At Barclon and Shepshed the stones 

 are angular, and sometimes they lie in bands which may be traced to 

 some crag projecting from the underlying rock slope (PI. XVI, 

 Fig. 3). 



In the most easterly quarry at Groby a coarse breccia rests upon the 

 rock, composed of angular fragments cemented together by white 

 calcareous matter. Here, also, large and very angular blocks of 

 beautifully fresh stone occur a few feet up in the marl. Their edges 

 are extremely sharp, and they bear no traces of water action, but look 

 rather as though they have been splintered off by frost action, and 

 have certainly received no rough treatment since. 



A scree sometimes forms the base of the Keuper when the slope 

 beneath is steep. The best example is seen in the quarry incline at 

 Croft, adjacent to an almost precipitous slope which faces south and is 

 seen in section to a depth of some 20 feet. The stones are sub- 

 angular and fresh (PL XVI, Eig. 4). The marl above also dips 

 steeply to the south, but the angle of rest was apparently less for the 

 fi.ne material than for the stones. 



